Chlamydia trachomatis is at present one of the most common sexually transmitted pathogens and has been established as an important cause of salpingitis. Salpingitis is one of the most severe forms of chlamydial infection in women often resulting in tubal scarring, a leading cause of preventable infertility. Little is known about the pathogenesis of chlamydial salpingitis in the human. To study chlamydial salpingitis, we have established a new animal model: the subcutaneous pocket model of oviductal tissue autografts in monkeys. The objectives of the proposed study are to elucidate the immunopathology of C. trachomatis salpingitis, and to evaluate immunity against infection and prevention of infection by immunization. The specific aims are to: 1) define the ultrastructure of attachment, entry, and development of C. trachomatis in vivo by transmission electron microscopy; 2) assess persistent infection and correlate inflammatory reactions and tissue damage with infection by culture, detection of chlamydial antigens and DNA, and reactivation; 3) identify and quantitate components of the cell mediated immune response by immunocytology and flow cytometry and by administration of cytokines; 4) evaluate the role of hypersensitivity reactions and analyze the antigens that cause hypersensitivity by injecting different antigens into sensitized pockets; 5) evaluate the effects of oral contraceptives on susceptibility of the female reproductive tract to infection with C. trachomatis and on inflammatory reactions; and 6) study the immunity and prevention of infection by vaccine of chlamydial salpingitis by immunization with inactivated whole organisms or fractionated antigens followed by inoculation with live organisms in the pockets to determine the specificity and duration of immunity, and to develop effective methods of immunization.